High-efficiency catalytic converters for treating exhaust gases

ABSTRACT

Several embodiments of high-efficiency catalytic converters and associated systems and methods are disclosed. In one embodiment, a catalytic converter for treating a flow of exhaust gas comprising a reaction chamber, a heating enclosure enclosing at least a portion of the reaction chamber, and an optional coolant channel encasing the heating enclosure. The reaction chamber can have a first end section through which the exhaust gas flows into the reaction chamber and a second end section from which the exhaust gas exits the reaction chamber. The heating enclosure is configured to contain heated gas along the exterior of the reaction chamber, and the optional coolant channel is configured to contain a flow of coolant around the heating enclosure. The catalytic converter can further include a catalytic element in the reaction chamber.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to U.S. Provisional ApplicationNo. 61/017,138, filed Dec. 27, 2007, the disclosure of which isincorporated herein in its entirety.

TECHNICAL FIELD

The technical field is related to catalytic converters for treatingexhaust gases, such as exhaust gases from internal combustion engines,power generators (e.g., coal or fossil fuels), and other sources ofexhaust gases.

BACKGROUND

Catalytic converters have been used to reduce emissions in exhaust gasesof internal combustion engines for many years. For example, catalyticconverters have been required for use in gas powered cars to removehydrocarbons, nitrogen oxide, carbon monoxide, and other contaminantsfrom exhaust gases. Catalytic converters have also been developed toprovide auxiliary heat to the passenger compartments of hybrid cars. Atypical catalytic converter includes a catalytic element, such as acatalytic core, contained in a housing. The catalytic element can be amonolithic catalyst with an open-pore structure having irregular andinter-connected flow paths for the exhaust gases, such as porous metalor ceramic materials, networks, or fiber structures. Other catalyticelements can have a honeycomb structure with regular flow channelsthrough which the exhaust gases flow. The catalyst can be platinum,ruthenium, or another suitable catalyst that removes the undesirableelements from the exhaust gases. In general, the catalysts require aminimum temperature to react with the emissions, and higher reactiontemperatures enhance the removal of emissions from the exhaust gases.Several conventional catalytic converters are relatively inefficientbecause the temperature at the center of the core is often much higherthan at the periphery. As a result, the peripheral portions of thecatalytic element typically have a lower reaction rate and lowerefficiency that reduces the overall efficiency of the catalyticconverter.

Although catalytic converters have been required in cars for many years,they have not been required in marine vessels with inboard or sterndrive engines. However, in 2009, catalytic converters will also berequired in new marine vessels with inboard or stern drive engines. Thisrequirement is challenging because it has been difficult to maintain asufficiently cooled exterior temperature for marine applications whilealso maintaining a sufficiently high temperature in the peripheralregions of the core to remove enough emissions to meet the standards ofthe Environmental Protection Agency (EPA). The core temperature ofconventional catalytic converters is typically 1,000-1,400° F. Inautomobile applications the exterior surfaces of the catalyticconverters are air cooled and have temperatures of about 600-1,000° F.Such high exterior temperatures significantly exceed the 200° F.exterior temperature limit set by the United States Coast Guard in itsregulations for marine vessels. Catalytic converters for marine vesselsare accordingly water cooled to reduce the exterior temperatures towithin acceptable limits. Water cooling the exterior of the catalyticconverters, however, further reduces the temperatures of the peripheralregions of the catalytic cores. Water cooled catalytic convertersaccordingly often have much lower efficiencies that result in higherhydrocarbon, nitrogen oxide, and carbon monoxide emissions.

One proposed solution for marine catalytic converters has a corecontained in a housing, a solid insulating blanket of asbestos or othersolid material around the core, and a water jacket around the insulatingblanket. To offset the heat loss at the periphery of the core, marinecatalytic converters may use more efficient and more expensive rutheniumcatalytic elements. Although this solution is an improvement, it isstill less efficient than catalytic converters for automobiles that useless expensive platinum catalytic cores. Moreover, although ruthenium orother core materials can be used to increase the efficiency, marinecatalytic converters still may not meet the standards of the EPA.

Additionally, even though current catalytic converters reduce theemissions from cars and other sources, the sheer number of vehicles inoperation have greatly contributed to the amount of hydrocarbons,nitrogen oxide, and carbon monoxide in the atmosphere. According to manystudies and models, the rapidly increasing levels of hydrocarbons,nitrogen oxide, and carbon monoxide emissions are contributing to anunprecedented rate of global warming that will likely have manyrepercussions. The rapid increase in the average temperatures beingreported have led many scientists to predict disastrous consequencesunless emissions are reduced significantly. Therefore, providing ahigh-efficiency catalytic converter that removes more emissions fromexhaust gases will protect the environment and mitigate the potentialconsequences of global warming.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a high-efficiency catalyticconverter in accordance with an embodiment of the disclosure.

FIG. 2 is a schematic view of a catalytic converter in accordance withanother embodiment of the disclosure.

FIG. 3 is a schematic view of a catalytic converter in accordance withyet another embodiment of the disclosure.

FIG. 4 is a schematic view of a catalytic converter in accordance withstill another embodiment of the disclosure.

FIG. 5 is a cross-sectional view of a catalytic converter in accordancewith another embodiment of the disclosure.

FIG. 6 is a cross-sectional view of a catalytic converter in accordancewith yet another embodiment of the disclosure.

FIG. 7 is a cross-sectional view of an alternative embodiment of thecatalytic converter of FIG. 6 in accordance with another embodiment ofthe disclosure.

FIG. 8 is a schematic diagram of a gas treatment system having acatalytic converter in accordance with another embodiment of thedisclosure.

FIGS. 9A-B are schematic diagrams of power generating systems having acatalytic converter in accordance with embodiments of the disclosure.

DETAILED DESCRIPTION A. Overview

The following disclosure describes several embodiments of catalyticconverters in the context of marine vessels for use with inboard or stemdrive internal combustion engines. For example, the describedembodiments of the catalytic converters are well suited for use inpleasure craft (e.g., ski-boats, yachts, fishing boats, etc.) andpersonal water crafts (e.g., “jet-skis” and “water bikes”). Although theembodiments of catalytic converters described below are well suited formarine vessels, they can also be used in industrial, automotive, orother applications in which it is desirable to remove emissions fromexhaust gases. Several embodiments of the catalytic converter mayaccordingly be used to remove hydrocarbons, nitrogen oxide, carbonmonoxide, and other emissions from coal fired generators, other types ofinternal combustion engines used in marine or other applications, orother applications that can benefit from highly efficient removal ofemissions from gases. Additionally, several other embodiments of thecatalytic converter can have different configurations, components, orprocedures than those described in this section. A person of ordinaryskill in the art, therefore, will accordingly understand that thecatalytic converter and associated gas treatment and/or power generatingsystems may have other embodiments with additional elements, or theinvention may have other embodiments without several of the featuresshown and described below with reference to FIGS. 1-9B.

One embodiment of a catalytic converter for treating a flow of exhaustgas comprises a reaction chamber, a heating enclosure enclosing at leasta portion of the reaction chamber, and an optional coolant channelencasing the heating enclosure. The reaction chamber can have a firstend section through which the exhaust gas flows into the reactionchamber and a second end section from which the exhaust gas exits thereaction chamber. The heating enclosure is configured to contain heatedgas along the exterior of the reaction chamber, and the optional coolantchannel is configured to contain a flow of coolant around the heatingenclosure. The catalytic converter can further include a catalyticelement in the reaction chamber.

Another embodiment of a catalytic converter for treating a flow ofexhaust gas comprises a reaction chamber having an inlet section and anoutlet section configured such that a primary flow of the exhaust gaspasses through the reaction chamber from the inlet section to the outletsection. The catalytic converter further includes a plenum surroundingthe reaction chamber, a first passageway between the reaction chamberand the plenum at the outlet section, and a second passageway betweenthe reaction chamber and the plenum at the inlet section. A portion ofthe primary flow of the exhaust gas passes through the plenum from thefirst port to the second port to generate a counter-flow of heated gasthrough the plenum. The catalytic converter can further include anoptional coolant channel surrounding the plenum, and a catalytic core inthe reaction chamber.

A method for reducing emissions from a flow of exhaust gas in accordancewith one embodiment comprises passing a primary flow of exhaust gas in afirst direction through a catalytic core in a reaction chamber andpassing a secondary flow of exhaust gas through a heating enclosurearound the reaction chamber. The method can further include passing aflow of cooling fluid through a coolant channel surrounding the heatingenclosure. Several specific examples of the foregoing embodiments ofcatalytic converters, gas treatment systems, power generation systems,and associated methods for reducing emissions and/or generating powerfrom a flow of exhaust gas are described below with reference to FIGS.1-9B.

B. Description of Specific Embodiments of Catalytic Converters

FIG. 1 is a schematic illustration of a high-efficiency catalyticconverter 100 that is well suited for applications that require limitedexternal temperatures and/or higher efficiencies. In this embodiment,the catalytic converter 100 includes a reaction chamber 110, a heatingenclosure 120 enclosing at least a portion of the reaction chamber 110,and a cooling channel 130 encasing at least a portion of the heatingenclosure 120. The reaction chamber 110 has a first end section 112through which a primary flow F_(p) of exhaust gas flows into thereaction chamber 110 and a second end section 114 from which the primaryflow F_(p) of exhaust gas exits the reaction chamber 110. The first endsection 112 can accordingly be an inlet section, and the second endsection 114 can be an outlet section. The heating enclosure 120 can be aplenum configured to contain a flow of heated gas F_(h) along theexterior of the reaction chamber 110, and the coolant channel 130 can bea cooling jacket configured to contain a coolant flow F_(c) around theheating enclosure 120. In the embodiment illustrated in FIG. 1, theheating enclosure 120 is an interior annular plenum concentricallyadjacent to a medial section of the reaction chamber 110, and thecoolant channel 130 is an outer annular jacket concentrically adjacentto the heating enclosure 120. The catalytic converter 100 furtherincludes a catalytic element 140 in the reaction chamber 110. Suitablecatalytic elements 140 include an open-pore matrix, such as porousmetals or ceramics, networks, or fiber structures, and a catalyst, suchas platinum, ruthenium, or other suitable catalysts depending upon thetype of exhaust gas. The catalytic element 140 can alternatively be ahoneycomb matrix or other matrix structures with the desiredcatalyst(s). The reaction chamber 110, heating enclosure 120, andcooling channel 130 operate together to enhance the efficiency of thecatalytic element 140 while also providing a much lower temperature atthe exterior of the catalytic converter.

In this embodiment, the reaction chamber 110 further includes one ormore first ports 115 toward the outlet section 114 and one or moresecond ports 116 toward the inlet section 112. The first ports 115 andthe second ports 116 can operate together to generate a counter-flowF_(h) of high temperature exhaust gas through the heating enclosure 120.The heated flow F_(h) enters the heating enclosure 120 through the firstports 115 and exits from the heating enclosure 120 through the secondports 116 so that a recirculation flow F_(r) enters back into theprimary flow F_(p) of exhaust gas. The counter-flow F_(h) through theheating enclosure 120 is extremely hot because it enters the heatingchamber 120 after it has been processed by the catalytic element 140.More specifically, the thermal reaction of the catalytic process heatsthe primary flow F_(p) of exhaust gases from an inlet temperature T_(i)of about 300-600° F. to an outlet temperature T_(o) of about1,000-1,400° F. As a result, the heated flow F_(h) provides an extremelyhot barrier with a low thermal conductivity between the catalyticelement 140 in the reaction chamber 110 and the coolant flow F_(c) inthe coolant channel 130. The heated flow F_(h) actively heats theexterior of the reaction chamber and accordingly mitigates heat lossfrom the reaction chamber 110 such that the peripheral regions of thecatalytic element 140 also have a very high temperature that is near thecentral core temperature. In contrast to conventional water-cooledcatalytic converters that do not actively heat the exterior of thereaction chamber, the catalytic converter 100 is highly efficient andremoves a very significant percentage of carbon monoxide, nitrogenoxide, hydrocarbons and/or other undesirable constituents from theprimary flow F_(p) of exhaust gas.

The coolant channel 130 contains a sufficient flow of coolant, such aswater or another suitable fluid, to cool an exterior surface 150 aroundthe heating enclosure 120 and/or the end sections of the reactionchamber 110. When the catalytic converter 100 is used in marineapplications for inboard or stem drive vessels, the coolant flow F_(c)can be a flow of raw water from the body of water supporting the vesselor a closed-loop system incorporating a heat exchanger. The coolant flowF_(c) removes the heat radially outwardly from the heating enclosure 120such that the exterior surface 150 is within a suitable operating rangefor the particular application. In the case of marine vessels, thecoolant flow F_(c) is sufficient such that the temperature of theexterior surface 150 is less than 200° F., and generally less than about160° F., during normal operation. For example, a specific prototype ofthe catalytic converter 100 tested in 45-60° F. ambient water has anexterior surface temperature of 80-120° F. and a core temperature in thecatalytic element 140 of about 1,100-1,400° F.

FIG. 2 is a schematic view of a catalytic converter 200 in accordancewith another embodiment of the disclosure. Like reference symbols referto like components in FIGS. 1 and 2. In this embodiment, the reactionchamber 110 of the catalytic converter 200 includes one or more ports201 through which the exhaust gases flow both in and out of the heatingenclosure 120. The ports 201 can have a scoop 202 that directs anin-flow F_(i) from the primary flow F_(p) into the heating enclosure120. An outflow F_(o) from the heating enclosure also occurs through theport 201. More specifically, when the pressure in the heating enclosure120 exceeds the pressure at the ports 201, the outflow F_(o) will passthrough the ports 201. The catalytic converter 200 is similar to thecatalytic converter 100, but the catalytic converter 200 does notproduce the same counter flow through the heating enclosure 120.

FIG. 3 is a schematic view of a catalytic converter 300 in accordancewith yet another embodiment of the disclosure, and like referencesymbols refer to like components in FIGS. 1-3. The catalytic converter300 has a heating channel or enclosure 320 that is completely distinctfrom the reaction chamber 110. In this embodiment, the heated flow F_(h)can comprise exhaust gases removed from the primary flow F_(p) upstreamfrom the catalytic converter 300 and then reintroduced to the primaryflow F_(p) downstream from the catalytic converter 300. As such, theheated flow F_(h) through the heating enclosure 320 is not processedthrough the catalytic element 140. The heated flow F_(h) in thecatalytic converter 300, therefore, is not as hot as the heated flowF_(h) in the catalytic converter 100. In another example of thisembodiment, the heated flow F_(h) can be raw air that is passed over theexterior of the exhaust manifold, the exterior of the exhaust pipe, orother heated portions of the engine to reach a reasonably hightemperature that still mitigates heat transfer away from the reactionchamber 110.

FIG. 4 is a schematic view of a catalytic converter 400 in accordancewith another embodiment of the disclosure, and like reference numbersrefer to like components throughout FIGS. 1-4. In this embodiment, thecatalytic converter 400 includes a reaction chamber 410 having a closedend 412 and a plurality of outlet ports 414. The catalytic converter 400further includes a heating enclosure 420 around the reaction chamber 410that includes a plurality of outlets 422, and a catalytic element 440 inthe reaction chamber 410. In this embodiment, the catalytic element 440has a matrix 442 that carries the catalyst and a central bore 444through the matrix 442. The coolant channel 130 surrounds the heatingenclosure 420 as explained above. In operation, the primary flow F_(p)flows in through the central bore 444 and then through the matrix 442 ofthe catalytic element 440. The primary flow F_(p) exits the reactionchamber 410 through the outlets 414 such that the heated flow F_(h) inthe heating enclosure 420 is the treated portion of the primary flowF_(p) exiting the reaction chamber 410. The primary flow F_(p) thenexits the heating enclosure 420 through the outlet ports 422 and isdirected out of the vessel. The catalytic converter 400 accordingly usesthe catalytic element 440 to heat the exhaust gas in the heatingenclosure 420.

FIG. 5 is a cross-sectional view of a catalytic converter 500 inaccordance with another embodiment of the disclosure. In thisembodiment, the catalytic converter 500 includes a reaction chamber 510,a heating enclosure 520 around at least a portion of the reactionchamber 510, and a coolant channel 530 around the heating enclosure 520and portions of the reaction chamber 510. The heating enclosure 520 is aplenum, and the coolant channel 530 is a jacket for containing a flow ofcoolant (e.g., water or another suitable liquid). In this embodiment,the catalytic element 540 has a matrix and a suitable catalyst asexplained above.

The reaction chamber 510 includes a first end section 511, a second endsection 512, and a central conduit 513 between the first end section 511and the second end section 512 in which the catalytic element 540 ispositioned. The first end section 511 includes a main inlet 514 throughwhich the primary flow F_(p) of exhaust gas enters the reaction chamber510. The first end section 511 further includes a diverging wall 515that has an increasing cross-sectional dimension from the end of themain inlet 514 to the central conduit 513. The second end section 512has a main outlet 516 through which the primary flow F_(p) of exhaustgas exits the reaction chamber 510. The second end section 512 furtherincludes a converging wall 517 with a decreasing cross-sectionaldimension in a direction away from the central conduit 513 toward themain outlet 516. As explained below, the configuration of the divergingwall 515 and converging wall 517 contribute to generating a consistentheated counter-flow F_(h) through the heating enclosure 520. Forexample, without being bound by theory, the diverging wall 515 isbelieved to contribute to creating an expansion zone upstream from thecatalytic element 540, and the converging wall 517 is believed tocontribute to creating a high pressure zone downstream from thecatalytic element 540.

The heating enclosure 520 has an inner housing 522 with a first portion523 attached to the first end section 511 of the reaction chamber 510, asecond portion 524 attached to the second end section 512 of thereaction chamber 510, and a medial portion 525 between the first portion523 and the second portion 524. The medial portion 525 is spacedoutwardly apart from the central conduit 513 of the reaction chamber 510such that the heating enclosure 520 comprises an enclosed space betweenthe inner housing 522 and the combination of exterior surfaces of thediverging wall 515, central conduit 513 and converging wall 517. Thecatalytic converter 500 in this embodiment also includes a plurality offirst ports 541 through the converging wall 517 and a plurality ofsecond ports 542 through the diverging wall 515. The first ports 541 andthe second ports 542 can further include flaps 543 that extend into theheating enclosure 520.

The reaction chamber 510, the heating enclosure 520, and the catalyticelement 540 operate together to generate a consistent counter flow ofhot gases around the exterior of the central conduit 513 of the reactionchamber 510 to mitigate heat losses that would otherwise reduce theefficiency of the catalytic element 540. More specifically, theconverging wall 517 and the flaps cause a portion of the exhaust gasesfrom the primary flow F_(p) to flow through the first ports 541 and intothe heating enclosure 520. Conversely, the diverging wall 515 upstreamfrom the catalytic element 540 and the flaps cause the gases to flow outof the heating enclosure 520 such that a heated counter-flow F_(h) flowsthrough the heating enclosure 520 in a direction opposite that of theprimary flow F_(p) through the reaction chamber 510. The heatedcounter-flow F_(h) is particularly advantageous because the catalyticelement 540 heats the exhaust gases from a temperature of approximately300-600° F. at the first end section 511 to approximately 1,000-1,400°F. at the second end section 512. As a result, the gases entering theheating enclosure 520 are near the temperature of the catalytic element540 itself. This high temperature gas flow through the heating enclosure520 accordingly mitigates heat losses at the periphery of the catalyticelement 540 so that the temperature gradient from the center of thecatalytic element 540 to its periphery is relatively low. Additionally,because the heated counter-flow F_(h) of gasses through the heatingenclosure 520 is introduced as a recirculation flow F_(r) upstream fromthe catalytic element 540, this portion of the exhaust gasses isreprocessed through the catalytic element 540 to further reduce thelevel of emissions in the primary flow F_(p) that exits through the mainoutlet 516 of second end section 512.

The coolant channel 530 can include an outer housing 532 spaced apartfrom an exterior surface of the inner housing 522 and a flow channel 533defined, at least in part, by the space between the inner housing 522and the outer housing 532. In this embodiment, the outer housing 532 hasa first end 534 with an inlet 535 and a second end 536 with an inlet537. The first end 534 can surround a portion of the first end section511 of the reaction chamber 510 upstream from the first portion 523 ofthe heating enclosure 520, and the second end 536 can surround a portionof the second end section 512 of the reaction chamber 510 downstreamfrom the second portion 524 of the heating enclosure 520. Thisconfiguration of the coolant channel 530 accordingly cools the catalyticconverter 500 both upstream and downstream from the very hot heatingenclosure 520 to ensure that the exterior temperature of the catalyticconverter 500 is low enough for marine applications. In otherapplications, however, it may not be necessary to have a low exteriortemperature such that the coolant channel 530 does not necessarily needto extend over the reaction chamber 510 outside of the heating enclosure520.

The flow channel 533 can further include a flow guide 538 that guidesand/or divides the flow through the flow channel 533 to distribute thecooling fluid around the heating enclosure 520. In this embodiment, theflow guide 538 is a continuous, helical wall between the inner housing522 and the outer housing 532 that creates a helical channel along theexterior surface of the heating enclosure 520. The coolant flow F_(c)accordingly enters the inlet 535 and flows helically around the exteriorof the heating enclosure 520 until it exits the coolant channel 530 atthe outlet 537. The flow guide 538 is configured to distribute thecoolant flow F_(c) around the exterior surface of the heating enclosure520 so that air pockets are less likely to form in the coolant channel530 and/or the flow over the heating enclosure 520 is generallyconsistent. The flow guide 538 accordingly reduces the temperaturegradients from one portion of the heating enclosure 520 to another. Theflow guide 538 is optional depending upon the particular application.Additionally, in other embodiments, the flow guide 538 can be aplurality of individual walls extending lengthwise longditunally alongthe length, or at least a portion of the length, of the flow channel533.

FIG. 6 is a schematic view of a catalytic converter 600 in accordancewith another embodiment of the disclosure, and FIG. 7 is a schematicview of an alternative arrangement of the catalytic converter 600 inFIG. 6. Like reference symbols refer to like components in FIGS. 5-7. Inthis embodiment, the reaction chamber 510 of the catalytic converter 600can include features generally similar to the catalytic converter 500shown in FIG. 5. However, as shown in FIG. 6, instead of having thefirst ports 541 through the converging wall 517 and a plurality ofsecond ports 542 through the diverging wall 515, the catalytic converter600 includes a first collar 602 a having the first ports 541 and asecond collar 602 b having the second ports 542. The first and secondcollars 602 a and 602 b can carry the flaps 543 of the first and thesecond ports 541 and 542, respectively. The first and second collars 602a and 602 b can have a generally ring shape, a rectangular shape, and/orother suitable shapes.

Even though the catalytic converter 600 is shown in FIG. 6 as having theflaps 543 of the first ports 541 generally aligned with those of thesecond ports 542, in other embodiments, the flaps 543 of the first ports541 and those of the second ports 542 may be offset from one another.For example, as shown in FIG. 7, the flaps 543 of the first ports 541can be offset from those of the second ports 542 by about 90°. In otherexamples, the flaps 543 of the first ports 541 can be offset from thoseof the second ports 542 by about 10°, 20°, 30°, 45°, and/or othersuitable offset angles. The offset flaps 543 of the first and secondports 541 and 542 may help to reduce bypass of the heated counter-flowF_(h) of gasses through the heating enclosure 520 and the recirculationflow F_(r) through the reaction chamber 510.

In FIGS. 6 and 7, several embodiments of the catalytic converter 600 areshown to have the first and second collars 602 a and 602 b. In otherembodiments, one of the first and second collars 602 a and 602 b may beomitted. In further embodiments, the catalytic converter 600 may includeat least one of the first and second collars 602 a and 602 b thatindividually having a single flap 543, three flaps 543, or any otherdesired number of flaps 543. In yet further embodiments, at least one ofthe first and second collars 602 a may include a flap (not shown) with acompletely circular opening.

FIG. 8 is a schematic diagram of a gas treatment system 800 inaccordance with another embodiment of the disclosure. As shown in FIG.8, the gas treatment system 800 can include a catalytic converter 801coupled to a flow restrictor 802 downstream from the catalytic converter801. The catalytic converter 801 can include a reaction chamber 803carrying a catalytic element 805 and a cooling channel 804 surroundingthe reaction chamber 803. The cooling channel 804 can have a coolantinlet 835 and a coolant outlet 837. In certain embodiments, thecatalytic converter 801 can be generally similar in structure andfunction as several embodiments of the catalytic converter describedabove with reference to FIGS. 1-7. In other embodiments, the catalyticconverter 801 can also have other configurations and/or features. Forexample, the catalytic converter 801 can be generally similar to thecatalytic converter 100 in FIG. 1 except the catalytic converter 800does not include the heating enclosure 120.

In the illustrated embodiment, the flow restrictor 802 includes a checkvalve in fluid communication with the coolant outlet 837 of the coolingchannel 804. In other embodiments, the flow restrictor 802 can alsoinclude an orifice, a venturi, a nozzle, and/or other types of flowelement suitable for at least reducing a coolant flow from the catalyticconverter 801 or increasing a pressure drop of the coolant flowingthrough the cooling channel 804.

Several embodiments of the gas treatment system 800 can at least reducethe risk of overheating the catalytic converter 801 when a supplypressure of the coolant is insufficient. For example, in certainembodiments, the gas treatment system 800 may be used in a marine vesselthat has an on-board water supply. When in water, the on-board watersupply can provide sufficient pressure to force water through thecooling channel 804 of the catalytic converter 801. When the marinevessel is on land (e.g., towed on a trailer), the water in the catalyticconverter 801 tends to drain out from the cooling channel 804 via thecoolant outlet 837. Without the water, the catalytic element 805 mayoverheat and fail because the catalytic reaction may still be active dueto residual gases in the reaction chamber 803 and/or the thermal inertiaof the catalytic element 805. Accordingly, by incorporating the flowrestrictor 802, at least some water would remain when the marine vesselis out of the water to at least reduce the risk of overheating thecatalytic converter 801.

Even though the coolant outlet 837 is shown in FIG. 8 is at a bottomportion of the catalytic converter 801, in other embodiments, thecoolant outlet 837 may be at a top portion of the catalytic converter801, as shown in phantom lines in FIG. 8. In further embodiment, thecatalytic converter 801 may include both a first coolant outlet (notshown) at a top portion and a second coolant outlet (not shown) at abottom portion of the catalytic converter 801. At least one flowrestrictor 802 may be in fluid communication with the first and secondcoolant outlets.

FIGS. 9A-B are schematic diagrams of a power generating system 900 inaccordance with embodiments of the disclosure. As shown in FIG. 9A, thepower generating system 900 can include an engine 901, a catalyticconverter 902, a steam turbine 911, and an optional heat exchanger 914interconnected with one another. The engine 901 can include a gasolineengine, a diesel engine, a gas turbine, and/or other gas-burningequipment. Alternatively, as shown in FIG. 9B, the power generatingsystem 900 can include an industrial gas source 903 (e.g., a powerplant, a synthetic gas reactor, etc.) instead of the engine 901. Infurther embodiments, the power generating system 900 may include acombination of at least one engine 901 and industrial gas source 903.

As shown in FIG. 9A, the catalytic converter 902 can include a gas inlet904 coupled to the engine 901 and a gas outlet 906 open to vent. Thecatalytic converter 902 can also include a fluid inlet 908 and a fluidoutlet 910. The fluid outlet 910 can be coupled to the steam turbine911. In certain embodiments, the catalytic converter 902 can begenerally similar in structure and function as several embodiments ofthe catalytic converter described above with reference to FIGS. 1-7. Inother embodiments, the catalytic converter 902 can also have otherconfigurations and/or features. In the illustrated embodiment, the steamturbine 911 can be coupled to an electrical generator 912. In otherembodiments, the steam turbine 911 can also be coupled to a gascompressor, a pump, a drive shaft, and/or other suitable powerequipment.

In operation, the engine 901 produces an exhaust gas with impurities(e.g., carbon monoxide, nitrogen oxides, etc.). The catalytic converter902 receives the exhaust gas and reacts the impurities with air, oxygen,and/or other suitable composition to produce heat. The catalyticconverter 902 then receives a fluid (e.g., water) at the fluid inlet 908and raises the energy content of the fluid with the produced heat fromreacting the impurities. In the illustrated embodiment, the catalyticconverter 902 converts the received fluid (e.g., water) into steam andsupplies the steam to the steam turbine 911, which drives the electricalgenerator 912 for producing electricity. The optional heat exchanger 914can then condense and/or cool the steam and/or condensate from the steamturbine 911. The condensate may be returned to the catalytic converter902, discharged to drain, and/or otherwise disposed of.

A specific embodiment of the catalytic converter 500 was tested in anin-board marine vessel using a raw water flow through the coolantchannel 530. The raw water had a temperature of approximately 45-60° F.The catalytic element 540 exhibited a small temperature drop from thecenter of the core to the peripheral regions such that the temperatureof the core from the center to the perimeter was approximately1100-1400° F. at operating speeds. The temperature at the exteriorsurface of the coolant channel 530, however, was generally in the rangeof 70-120° F., and generally less than 100° F. even at high operatingspeeds. The catalytic converter removed a significant percentage ofhydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO). Theextremely low emissions from the catalytic converter 500 were asignificant improvement over conventional water cooled catalyticconverters and an even more surprising improvement over existingair-cooled catalytic converters used in cars. More specifically, theemissions tests for an embodiment of the catalytic converter 500 used ona Ramjet EFI, 6.3 L, 530 hp engine, are set forth in Table 1 below.

2600 rpm Stabilized readings Stabilized Velocity (GPS) 26 mph Units HC34 ppm CO 0.01 % CO2 13.7 %

The catalytic converter 500 also provided significant noise abatementcompared to systems without the catalytic converter. Without being boundby a theory, the heating enclosure 520 and coolant channel 530 appear tosignificantly dissipate acoustic energy in a manner that reduces thedecibel level of the primary flow of F_(p) of exhaust downstream fromthe catalytic converter 500. As a result, the catalytic converter 500 isfurther useful in marine applications and other applications in whichnoise pollution is a factor.

A specific embodiment of the catalytic converter 500 was further testedin an in-board marine vessel using a raw water flow through the coolantchannel 530 under various engine conditions. An atmospheric analyzerprovided by Speedtech (Model No. SM-28) was used to measure wind speed(both high and low), relative humidity, air temperature, and barometricpressure, as listed below:

Wind Speed-high 0 mph Wind Speed-low 0 mph Relative Humidity 63 % AirTemp 44 ° F. Barometric Pressure 1024 mbar

A gas analyzer provided by Snap-On Equipment of Conway, Ark. (Model No.EEEA305A) was used to measure hydrocarbon (HC), carbon dioxide (CO₂),carbon monoxide (CO), oxygen (O₂), nitrogen oxides (NO_(x)), andair-to-fuel ratio (AIF). A GPS meter provided by II Morrow (Model No.430-0265-41) was used to measure a speed in miles per hour (MPH) of themarine vessel. The collected data are presented in the tables below.

RPM 650 650 1000 1500 2000 Neutral Load Load Load Load HC ppm 91 30 1114 15 CO₂ % 14.36 14.52 14.42 14.78 14.84 O₂ % 0.17 0.04 0 0.03 0.01 CO% 0.055 0.02 0.197 0.255 0.132 A/F 15.33 15.3 15.2 15.2 15.24 NO_(x) ppm11 22 15 17 31 MPH 0 7 8 13 24 RPM 2500 3000 3500 4000 4500 Load LoadLoad Load Load HC ppm 23 44 47 82 81 CO₂ % 14.82 14.52 14.33 13.41 13.11O₂ % 0.02 0 0.03 0.02 0.02 CO % 0.202 0.357 0.698 2.042 2.886 A/F 15.2115.12 14.99 14.39 14.07 NO_(x) ppm 47 134 138 474 358 MPH 32 38 43 50 57

From the foregoing, it will be appreciated that specific embodiments ofthe disclosure have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the disclosure. For example, in certain embodiments,several embodiments of the catalytic reactors shown in FIGS. 1-7 may notinclude the cooling channel for automotive and/or other suitable uses.Accordingly, the disclosure is not limited except as by the appendedclaims.

1. A catalytic converter for treating a flow of exhaust gas, comprising:a reaction chamber having a first end section through which the exhaustgas flows into the reaction chamber and a second end section from whichthe exhaust gas exits the reaction chamber; a heating enclosureenclosing at least a portion of the reaction chamber, the heatingenclosure being configured to contain and recirculate a heated gas alongthe exterior of the reaction chamber; and a catalytic element in thereaction chamber.
 2. The catalytic converter of claim 1, furthercomprising a coolant channel encasing the heating enclosure, the coolantchannel being configured to contain a flow of coolant around the heatingenclosure.
 3. The catalytic converter of claim 2 wherein: the reactionchamber has a central conduit between the first end section and thesecond end section; the heating enclosure has an inner housing having afirst portion attached to the first end section of the reaction chamber,a second portion attached to the second end section of the reactionchamber, and a medial portion spaced outwardly apart from the centralconduit such that the heating enclosure comprises an enclosed spacebetween the central conduit and the inner housing; and the coolantchannel has an outer housing spaced outwardly apart from the innerhousing and a flow channel defined by the inner housing and the outerhousing.
 4. The catalytic converter of claim 2 wherein: the reactionchamber has a central conduit between the first end section and thesecond end section, the first end section has a diverging wall with anincreasing cross-sectional dimension toward the central conduit, thesecond end section has a converging wall with a decreasingcross-sectional dimension away from the central conduit, a first portthrough the converging wall, and a second port through the divergingwall; the heating enclosure has an inner housing having a first portionattached to the first end section of the reaction chamber upstream fromthe second port, a second portion attached to the second end section ofthe reaction chamber downstream from the first port, and a medialportion spaced outwardly apart from the central conduit such that theheating enclosure comprises an enclosed space between the centralconduit and the inner housing; and the coolant channel has an outerhousing spaced apart from an exterior surface of the inner housing and aflow channel defined by the inner housing and the outer housing.
 5. Thecatalytic converter of claim 2 wherein: the reaction chamber has acentral conduit between the first end section and the second endsection, the first end section has a diverging wall with an increasingcross-sectional dimension toward the central conduit and a first collarextending from the diverging wall, the second end section has aconverging wall with a decreasing cross-sectional dimension away fromthe central conduit and a second collar extending from the convergingwall, wherein the first collar has a first port, and wherein the secondcollar has a second port; the heating enclosure has an inner housinghaving a first portion attached to the first end section of the reactionchamber upstream from the second port, a second portion attached to thesecond end section of the reaction chamber downstream from the firstport, and a medial portion spaced outwardly apart from the centralconduit such that the heating enclosure comprises an enclosed spacebetween the central conduit and the inner housing; and the coolantchannel has an outer housing spaced apart from an exterior surface ofthe inner housing and a flow channel defined by the inner housing andthe outer housing.
 6. The catalytic converter of claim 2 wherein thecoolant channel further comprises a helical flow guide between the innerhousing and the outer housing such that the flow channel extendshelically around an outer surface of the inner housing.
 7. The catalyticconverter of claim 1 further comprising a port between the reactionchamber and the heating enclosure through which heated gas flows intoand out of the heating chamber.
 8. A catalytic converter for treating aflow of exhaust gas, comprising: a reaction chamber having an inletsection and an outlet section, wherein a primary flow of the exhaust gaspasses through the reaction chamber from the inlet section to the outletsection; a plenum surrounding the reaction chamber; a first passagewaybetween the reaction chamber and the plenum at the outlet section and asecond passageway between the reaction chamber and the plenum at theinlet section, wherein a portion of the primary flow of the exhaust gaspasses through the plenum from the first port to the second port togenerate a counter-flow of heated gas through the plenum; and acatalytic core in the reaction chamber.
 9. The catalytic converter ofclaim 8 wherein: the reaction chamber has a conduit between the inletsection and the outlet section; the plenum has an intermediate wallspaced outwardly apart from the conduit such that the plenum comprisesan enclosed space between the inner wall and the conduit; and whereinthe catalytic converter further includes a coolant channel surroundingthe plenum, and wherein the coolant channel has an outer wall spacedapart from the intermediate wall such that the coolant channel comprisesa flow channel between the intermediate wall and the outer wall.
 10. Thecatalytic converter of claim 9 wherein the coolant channel comprises ahelical divider between the intermediate wall and the outer wall suchthat the coolant channel extends helically around an outer surface ofthe intermediate wall.
 11. The catalytic converter of claim 8 whereinthe inlet section has an increasing cross-sectional dimension creatingan expansion zone upstream from the catalytic core relative to a primaryflow through the catalytic core and the outlet section has a decreasingcross-sectional dimension creating a high-pressure zone downstream fromthe catalytic core relative to the primary flow.
 12. The catalyticconverter of claim 11 wherein the first passageway is an aperturethrough the outlet section, the second passageway is an aperture throughthe inlet section, and the catalytic converter further comprises a firstflap at the first passageway and a second flap at the second passageway,and wherein the first and second flaps project into the plenum.
 13. Amethod for reducing emissions from a flow of exhaust gas, comprising:passing a primary flow of exhaust gas in a first direction through acatalytic core in a reaction chamber; passing a secondary flow ofexhaust gas through a heating enclosure around the reaction chamber; andpassing a flow of cooling fluid through a coolant channel surroundingthe heating enclosure.
 14. The method of claim 13, further comprisingextracting the secondary flow of exhaust gas from the primary flow ofexhaust gas after the primary flow of exhaust gas has passed through thecatalytic core and directing the secondary flow of exhaust gas throughthe heating enclosure.
 15. The method of claim 14, further comprisingdirecting the secondary flow of exhaust gas through the heatingenclosure in a second direction opposite the first direction of theprimary flow of exhaust gas and introducing the secondary flow ofexhaust gas back into the primary flow of exhaust gas upstream of thecatalytic core relative to the primary flow of exhaust gas.
 16. Themethod of claim 13, further comprising passing the flow of cooling fluidalong a helical path around the heating enclosure.
 17. The method ofclaim 13, further comprising: extracting the secondary flow of exhaustgas from the primary flow of exhaust gas after the primary flow ofexhaust gas has passed through the catalytic core; directing thesecondary flow of exhaust gas through the heating enclosure in a seconddirection opposite the first direction of the primary flow of exhaustgas; introducing the secondary flow of exhaust gas back into the primaryflow of exhaust gas upstream of the catalytic core relative to theprimary flow of exhaust gas; and passing the flow of cooling fluid alonga helical path around the heating compartment.